Laser trapping of a metallic probe for near field microscopy

A metallic particle is an ideal scattering probe in near-field microscopy. The Laser trapping technique, which enables us to capture a microscopic object using radiation pressure force, has been applied to trap a nanometer-sized metallic particle and to scan the particle over a sample surface as a near-field probe. In this section the mechanism and experimental verification of three-dimensional laser trapping of a metallic particle are explained. The trapping force on a gold particle is greater than that on a glass particle when these particles are sufficiently small compared to the wavelength of light. Also the development of laser trapping NSOM is described. Observed images on various samples using 40 nm diameter gold particles are shown.